1. Field of the Invention
The present invention is generally concerned with a support device to which any kind of object can be fixed temporarily, for example a device of the type usually associated with a contour reading device for securing an object whose contour or part of whose contour is to be read relative to the follower of the contour reading device.
It is more particularly directed to the case where the object concerned is an eyeglass frame and the contour of the rims or surrounds of the frame is to be read for the purpose of trimming the lenses to be mounted in the frame.
2. Description of the Prior Art
Eyeglass frame support devices usually comprise, disposed on a plate, a plurality of retaining means adapted to support an eyeglass frame over a hole or cavity in the plate.
This is the case, for example, with the support devices that are the subject matter of French patents Nos. 2 016 998, 2 124 265 and 2 319 076.
In the case of a contour reading device, the follower operates through the hole or cavity in the plate.
Usually consisting of pistons or slide members, the retaining means employed in these support devices in practise operate in specific radial directions.
This entails individual manipulation of each retaining means and their overall use is therefore relatively difficult and time consuming.
What is more, if the corresponding manipulation is not executed correctly it may lead to distortion of the eyeglass frame so that the subsequent contour reading is falsified.
It is therefore difficult with a support device kind to allow for the often pronounced curvature or meniscus-like shape of the rims or surrounds of the eyeglass frame.
However, this curvature can affect the inclination of the rim or surround when its contour is read.
Assuming that the eyeglass frame as a whole is laid flat, the "inclination" of a rim or surround means in this context the angle of the mean plane of the rim or surround to a reference plane passing through the median axis of symmetry of the frame.
It is clear that, depending on this inclination, the perimeter as read is different to a greater or lesser degree from the actual perimeter of the rim or surround concerned, the parameter read being that of the corresponding projection cylinder.
In practice, the greater the inclination of an eyeglass frame rim or surround on a support device the smaller the perimeter that is read.
There is therefore the risk that the lens trimmed according to this reading could be too small for the rim or surround to which it is to be fitted so that it could inadvertently fall out of the latter.
To avoid this risk the usual practice is to increase systematically the results of the reading obtained so that the trimmed lens is definitely too large for the rim or surround concerned, the lens being then "retouched" to fit it to the frame.
However, the retouching operation inevitably wastes considerable time.
What is more, the results can only be somewhat imperfect.
A general object of the present invention is a support device, especially one for eyeglass frames, that is free of these disadvantages and has additional advantages.